Sound box



F. STEVENS.

SOUND BOX.

APPLICATION FILED APR.28,1920.

1,4 1 9 ,7 7%. I Patented June 13, 1922.

HE. E.

F 1 527]: SZQVQJYS- INVENTIIIRL A TTE] FQNEY- UNITED STATES PATENT omen.

FRANK STEVENS, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR TO CHARLES R. KEEG-AN, OF PHILADELPHIA, PENNSYLVANIA.

SOUND BOX.

Specification of Letters Patent. V Patented June 13, 1922.

Application filed April 28, 1920. Serial No. 377,406.

To all whom it may concern:

Be it known that I, FRANK STEVENS, a citizen of the United States,- residing at Philadelphia, in the county of Philadelphia. and State of Pennsylvania, have invented a new and useful .Sound Box, of which the following is a specification.

My invention relates to sound boxes for the reproduction of phonographic sounds and its objects are to lmprove the'distinctness and clearness of enunciation as well as to amplify the volume of such sounds, and to provide a simple means of varying the angular relation between the needle and a 'record upon which it is operating.

I attain these objects by the combination of twin diaphragms with other specially devised members as is fully set forth and explained in the following description and the accompanying drawings, in which- Figure 1 is a side elevation, partly in ver- 'tical central section, and with parts broken away to disclose underlying construction; Figure 2, a horizontal central section through the line 2-2 of Figure 1; Figure 3, a perspective of the adjustable base for the stylus arm; and, Figures 4 and 5, perspective views of the two component parts of the stylus arm.

Similar indices refer to similar parts throughout the several views.

It will be first understood, as may be seen from the broken straight lines in Figure 1 and in the general lines of Figure 2, that I construct an interior sound chamber which is substantially a pyramidal bell-shaped structure having two opposite sides com posed of thin resonant material, upon which press the tips of a bifurcated stylus arm.

The body, 1, of the sound box is annular in shape and has a tubular stem, 2, into which is secured the tone arm joint 9. Into this body are fitted two diaphragms, 5, oppositely disposed, but not in parallel planes. They are so inclined that while relatively close together at the point most distant from the outlet a, in the stem 2, they will be farthest apart at their. nearest approach to this, outlet, whereby the bell-shapedchamber is partially formed. Each diaphragm 5 rests on an 'annular flange 4 integral with the body 1, and is retained by a resilient gasket 6, held into firm contact with it by a locking ring 7 threaded into the body -1 as shown at d.

Each diaphragm 5 may be enclosed'within an outside cover,-8, similarly threaded into and having a central opening, f, for the introduction of the stylus-arm tips, 11. In

this mode of construction it is obvious that the locking rings 7.may be dispensed with and the covers 8 so formed as to screw 'down tightly upon the washers 6, although in the drawings I have shown the locking rings encased beneath the covers 8, which are annularly channeled at their lower edges to receive the rings.

Between the flanges 4, is a septum 3, relatively thin at the point Where the diaphragms are closest and gradually increasing in thickness as it approaches the stem 2. From this septum is removed a slightly tapered sector so as to form an open sound channel, 6, leading into the outlet, (1, through the stem 2 and the tone arm joint 9. The two opposite divergent sides thereof constitute the intermediate walls between the diaphragm formed sides of the bell shaped chamber. These walls are preferably curvilinear so as to present opposite concavities whereby the shape of any transverse section across the interior sound chamber will be substantially a flattened ellipse between the diaphragms, and thence outwardly a series of progressively. expanding ellipses until a perfect;v circle is formed where the four sides assume that shape at the interior junction of the stem 2 with the tone arm joint 9.

Into firm spring pressed contact with each diaphragm 5 is the tip of a bifurcated portion 10 of the stylus-arm. This memher is firmly fitted into a channel, 71, formed in the T-shaped needle carrier member of the stylus-arm, where it is securely screwed through the holes Gr so as to be "rigidly retained. The T-shaped member is pivotally mounted between standards 15, by means of the conical bearings 17, which are threaded through these standards and are normally secured by the lock nuts, 18. The

In order that the angle at which the needle meets the plane of the record, 1', may be adjusted, irrespective of the normal,

, this character, I

in. This base,

axial line 2-2 in Figure 1, when my sound box is adjusted to the tone arm, I have devised the following construction whereby the stylus-arm may be oscillated about the contact point 11 on the diaphragms as a centre:

In the periphery of the body member, 1, is formed a longitudinal channel, 0, extending for a suflicient part of a circle to. enable a slidable correspondingly arc-shaped base, 16, to be moved, back and forth, therewhich is the foundation from which the standards 15 extend, is formed to be snugly and smoothly engaged between the sides of the channel 0, so as to be accurately guided thereby when moved for adjustment purposes, whereby the exact central relation between the tips 11 and the diaphragms 5 may not be disturbed. To afford reliable means whereby this base may be securely ,retained as adjusted to any desired position, there are two longitudinal slots, 20, cut through its centre, through each 0st 19, securely imbedded in the annular Body-portion, 1, and of a diameter accurately corresponding to the Width of the slots. On each post thus radially proecting from the' body 1 is a binding nut, 21, which is screwed down so as to firmly clam the base to the body on both sides of t e stylus-arm. These slots and posts afford further guiding means for assuring accuracy of the motion of the stylus-arm about the centre 11.

For obtaining the greatest sweetness and ,purity of reproduction in a sound box of believe the most satisfactory material to be hard rubber and I therefore, have formed the annular body portion 1, with its stem 2 and septum 3, as well as the cover members, 8, out of this substance. The diaphragms, 5, may be mica, or any other of the time-proved materials, while the binding rings, 7 the stylus arm and its accessories are preferably of metal. The tone arm joint is also of metal.

It will be observed that the covers 8 are of such depth or thickness that when screwed into properly secured position the opposite outside faces of the sound box will be perfectly smooth and flush, and the general contour of the apparatus resemble a blunt circular wedge having a radial" stem at its thickest portion. This severely plain design in combination with the dead black finish of the hard rubber composition and the contrasting metallic stylus arm and other attachments presents a very attractive and pleasing appearance.

For the purpose of illustrating my invention, I have shown in the accompanying views and described herein the form thereof at present preferred by me, although it is to be understood that the various inof which extends a threaded binding;

strum'entalities of which my invention consists can be variously arranged and organized and that my invention is not to be limited to the precise arrangement and organization herein shown and described, and that I hereby reserve the right to reorganize and rearrange these instrumentalities within'the scope of my claims.

I am aware that prior to my invention sound boxes have been made with twin diaphragms and I do not therefore claim such a feature broadly, but I do claim:

1. In a sound box, in combination, a vacant chamber, resilient walls thereto, a stylus, a stylus arm so forked as to transmit sound impulses from said stylus to each wall independently, an outlet from said cham her, and means to adjust said stylus with relation to said outlet.

2. In a sound box, in combination, a tapered vacant chamber, resilient walls thereto, a stylus, sound transmitting means from-said stylus to said walls, an outlet from said chamber tapered symmetrically therewith, and means to adjust said stylus with relation to said outlet. l

3. In a sound box, in combination, a tapered vacant chamber, resilient plane walls thereto, so positioned as to form the taper thereof, a stylus, and a stylus arm so forked as to transmit sound impulses from said stylus to each wall independently.

-l. In a sound box, in combination, a tapered vacant chamber, resilient walls thereto, astylus, a stylus arm so forked as to transmit sound impulses from said stylus to each wall independently, an outlet from said chamber tapered symmetrically therewith, and means to adjust said stylus with relation to said outlet.

A sound box comprising a body member. a tapered channel therethrough, a movable stylus carrier thereon, means to angula rl'y ad just said carrier with relation to said channel, a pair of diaphragms oppositely disposed therein and diverging symmetrically toward said channel, a partial septum between said diaphragms, concave walls oppositely formedthereby, a concaver'eflecting part formed therein opposite to the outlet of said channel, stylus arms, one each independently connecting one of said diaphragms with said stylus carrier, and a pair of closures for saidbody member positioned respectively adjacent and parallel with each of said diaphragms.

6. In combination with a sound box casing a sound generating chamber therefor comprising resilient walls, concave walls alternately positioned therewith, a tapered outlet through said casing, toward which all of said walls diverge symmetrically, and a poncave reflecting wall opposite to said outet. a

7. In combination with an annular sound box having a peripheral outlet, stylus adbox casing and protruding radially through justment means comprising an annular pesaid slots, and manually rotatable clamping 10 ripheral channel in said casing, an arcuate nuts on said posts, all substantially as destylus arm carrier therein, bearings for a scribed.

stylus arm centrally positioned on said car- FRANK STEVENS. rier, slots through said carrier oppositely Witnesses: extending longitudinally from said bear- ALLEN S. WAY,

v ings, threaded posts imbedded in said sound -J. J. BOLESTRIDGE. 

